1 .. SPDX-License-Identifier: BSD-3-Clause
2 Copyright(c) 2017 Intel Corporation.
4 Traffic Metering and Policing API
5 =================================
11 This is the generic API for the Quality of Service (QoS) Traffic Metering and
12 Policing (MTR) of Ethernet devices. This API is agnostic of the underlying HW,
13 SW or mixed HW-SW implementation.
15 The main features are:
17 * Part of DPDK rte_ethdev API
18 * Capability query API
19 * Metering algorithms: RFC 2697 Single Rate Three Color Marker (srTCM), RFC 2698
20 and RFC 4115 Two Rate Three Color Marker (trTCM)
21 * Policer actions (per meter output color): recolor, drop
22 * Statistics (per policer output color)
23 * Chaining multiple meter objects
28 The metering and policing stage typically sits on top of flow classification,
29 which is why the MTR objects are enabled through a special "meter" action.
31 The MTR objects are created and updated in their own name space (``rte_mtr``)
32 within the ``librte_ethdev`` library. Whether an MTR object is private to a
33 flow or potentially shared by several flows has to be specified at its
36 Once successfully created, an MTR object is hooked into the RX processing path
37 of the Ethernet device by linking it to one or several flows through the
38 dedicated "meter" flow action. One or several "meter" actions can be registered
39 for the same flow. An MTR object can only be destroyed if there are no flows
45 Traffic metering determines the color for the current packet (green, yellow,
46 red) based on the previous history for this flow as maintained by the MTR
47 object. The policer can do nothing, override the color the packet or drop the
48 packet. Statistics counters are maintained for MTR object, as configured.
50 The processing done for each input packet hitting an MTR object is:
52 * Traffic metering: The packet is assigned a color (the meter output color)
53 based on the previous traffic history reflected in the current state of the
54 MTR object, according to the specific traffic metering algorithm. The
55 traffic metering algorithm can typically work in color aware mode, in which
56 case the input packet already has an initial color (the input color), or in
57 color blind mode, which is equivalent to considering all input packets
58 initially colored as green.
60 * There is a meter policy API to manage pre-defined policies for meter.
61 Any rte_flow action list can be configured per color for each policy.
62 A meter object configured with a policy executes the actions per packet
63 according to the packet color.
65 * Statistics: The set of counters maintained for each MTR object is
66 configurable and subject to the implementation support. This set includes
67 the number of packets and bytes dropped or passed for each output color.
72 .. _figure_rte_mtr_chaining:
74 .. figure:: img/rte_mtr_meter_chaining.*
78 This section will introduce the reader to the critical APIs to use
79 the traffic meter and policing library.
81 In general, the application performs the following steps to configure the
82 traffic meter and policing library.
84 #. Application gets the meter driver capabilities using ``rte_mtr_capabilities_get()``.
85 #. The application creates the required meter profiles by using the
86 ``rte_mtr_meter_profile_add()`` API function.
87 #. The application creates the required meter policies by using the
88 ``rte_mtr_meter_policy_add()`` API function.
89 #. The application creates a meter object using the ``rte_mtr_create()`` API
90 function. One of the previously created meter profile
91 (``struct rte_mtr_params::meter_profile_id``) and meter policy
92 (``struct rte_mtr_params::meter_policy_id``) are provided as arguments
94 #. The application enables the meter object execution as part of the flow action
95 processing by calling the ``rte_flow_create()`` API function with one of the
96 flow action set to ``RTE_FLOW_ACTION_TYPE_METER`` and the associated
97 meter object ID set to this meter object.
98 #. The API allows chaining the meter objects to create complex metering topology
99 by the following methods.
101 * Adding multiple flow actions of the type ``RTE_FLOW_ACTION_TYPE_METER`` to
103 Each of the meter action typically refers to a different meter object.
105 * Adding one (or multiple) actions of the type ``RTE_FLOW_ACTION_TYPE_METER``
106 to the list of meter actions (``struct rte_mtr_meter_policy_params::actions``)
107 specified per color as show in :numref:`figure_rte_mtr_chaining`.